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A rocket instrumented to measure Lyman alpha and X‐rays was fired while a small flare was in progress on June 20, 1956. The rocket reached peak altitude about ten minutes after the flare was first seen visually. An unusually high X‐ray flux was observed extending to a short wavelength limit of 3A. Although the flare was still visible in Hα, Lyman alpha was not appreciably different from normal.

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By means of proportional counters the ionization energy losses in gases of fx mesons of several high-energy groups have been compared with the loss for mesons at minimum ionization. It is shown that in a normal proportional counter and Geiger counter telescope arrangement as was used in this work, the effects of locally generated showers and counter-wall-generated secondary electrons tend to mask the increase in ionization loss accompanying increasing ju-meson energy. When such effects are considered, the theoretical rise as predicted by the Bethe-Bloch-Williams theory is confirmed. * Based, in part, on a dissertation submitted by one of the authors (J. E. K.) to the Graduate School of the University of North Carolina in partial fulfillment of the requirements for the degree of Doctor of Philosophy.t Supported by the U. S. Atomic Energy Commission. I Now on active duty with the U. S. Navy.

The observations obtained by rocket‐borne instruments carried to the altitude of about 120 km or higher at White Sands, New Mexico, suggest that there exists a directional variation of the Lyman‐α intensity that is correlated with the geomagnetic field. This correlation consists of three features: namely (1) the general increase of the flux in the direction of the geomagnetic north pole and the general decrease in the direction of the geomagnetic equator; (2) a trough of lower intensity along the geomagnetic dipole plane containing the observer's geomagnetic zenith; and (3) the symmetric increase of the flux on both sides of the trough. Also, the direction of decrease does not agree with the antisolar direction, as was previously thought. This suggests an association of the Lyman‐α emission with the Van Allen radiation belts. New interpretation proposed in this paper principally attributes the diffused nighttime Lyman‐α radiation to the collision between the neutral hydrogen atoms and the charged particles in the radiation belts, though there will be some contribution from the scattered solar Lyman‐α photons and the Lyman‐α photons of interstellar origin.